I bought one about six years ago for my previous truck & tall metal cap and still use it. Although it does help some with my new/old truck and Montana, I believe it only gains about 1/2 to 1 mpg. What you'd get would depend on how streamlined the front of your trailer is. You've also got to mount it as close to the trailer as you can get for best effectiveness. I've seen some larger ones, but they're far more expensive and I don't know as they are as easy to use as an Aero Shield
2010 Montana 3665RE, wet bolts, etc.
2006 Ford F350 Diesel Dually, air bags, Softopper, Aeroshild, etc.